Motoring: Like a cat out of hell

Some say Jaguar's XK8 isn't all it could be. Too soft, they declare, too much the image-enhancing boulevardier, not enough the driver-uplifting performance machine. It's fast, of course, and it looks curvily racy in the old Jaguar sports-car idiom, but it's no Nineties E-type. And they have a point.

Jaguar's engineers have always known this. When the XK8's V8 engine was unveiled two years ago, the project engineer Martin Joyce told me tales of wild XK8 engines they had concocted for various bizarre tests. "Some had open exhausts, and they sounded rather good. We're all petrolheads at heart here." Clearly, they were itching to create a truly sporting, hard-edged XK8, a car to show the world that Jaguar still knew how to do it instead of living on past glories. And now, with a year and a half's sales success behind it, the XK8 has been force-fed some power food and sent to the gym. The result is the Jaguar XKR, its 4.0-litre V8 engine's power pumped up by a supercharger, its suspension and steering made firmer, its rear tyres made stickier, its brakes made stronger.

You can recognise an XKR by its stainless steel mesh front grille, the E-type-like louvres on its bonnet, the 10-spoke wheels and the slim spoiler on its boot. Together, they signal the most ballistically rapid production Jaguar there has ever been. Peak power of 363bhp is why, plus a monstrous 372lb ft of pulling ability. The standard ZF transmission isn't strong enough to cope, so Jaguar buys its XKR units in from Mercedes-Benz.

The interior is unchanged from the XK8, although some of that car's sportier options are standard in the XKR. One of these is the Computer Active Technology Suspension (Cats), which automatically stiffens under acceleration, braking or cornering. The settings are modified for the XKR to give a crisper, sportier feel, helped further by firm and precise steering. You can properly sense what is going on under the wheels when you're cornering quickly, the better to enjoy the sort of agility and wieldiness you never quite get in the XK8.

This is as well, because things happen quickly when the supercharger is blowing hard into the engine. An electronic limiter is supposed to stop the Jaguar from straying beyond 155mph, assuming you ever have the chance; without it, 170mph or so would be possible. Such speeds are merely the by-product of vast power matched to gearing that's designed for serene and reasonably economical cruising at more normal speeds.

If the mood takes you, you can scorch to 60mph in 5.2 seconds. Just switch off the traction control, push the accelerator to the floor and let colossal thrust and the automatic transmission do the rest. You can overtake almost anything, engine woofling then building to a cackle the way V8s do, supercharger humming. You can choose a "sport" setting for the autobox, or select the five gears manually, but there's no point. Leave it to its own devices, let it slip seamlessly from gear to gear. I have never experienced a better automatic.

The power, the roadholding and the handling make the XKR as thrilling a big-hearted companion as you'll find this side of a Ferrari. It's a comfortable one, too, with its leather-trimmed cabin, CD stacker, air- conditioning and acreage of wood. It comes either as natural walnut or lacquered in translucent black, which would be my choice.

The other choice is between coupe and convertible. Either way, you won't find a more stimulating route to automotive relaxation. The XKR does all the things a Jaguar should, but it does them with a track-racer's edge. An E-type for the Nineties? Maybe. One of the most exciting and satisfying GT cars you can buy? That's nearer the mark.

JAGUAR XKR - Specifications

Prices: pounds 59,300 (coupe), pounds 66,300 (convertible).

Engine: 3996cc supercharged V8, 32 valves, 363bhp at 6,150rpm.

Transmission: Five-speed automatic gearbox, rear-wheel drive.

Performance: top speed 155mph, 0-60 in 5.2sec, 15-20mpg.

Rivals

Aston Martin DB7: pounds 84,950. Conceptually close to the XKR, supercharged but

uses a Jaguar-based six-cylinder engine. You pay for hand-built exclusivity, but it doesn't buy you a better car.

BMW 840Ci: pounds 57,470. Cheaper than Jaguar, but not as fast or as enjoyable to drive. Looks dramatic but is growing old now.

Porsche 911: from pounds 64,650. Latest 911 is a truly exciting drive, more 'physical' than Jaguar but less comfortable. Like DB7, can be had with manual transmission.